The Collaborative International Dictionary of English v.0.48:

Datura \Da*tu"ra\, n. [NL.; cf. Skr. dhatt[=u]ra, Per. & Ar.
   tat[=u]ra, Tat[=u]la.] (Bot.)
   A genus of solanaceous plants, with large funnel-shaped
   flowers and a four-celled, capsular fruit.
   [1913 Webster]

   Note: The commonest species are the thorn apple (D.
         stramonium), with a prickly capsule (see Illust. of
         capsule), white flowers and green stem, and Datura
         tatula, with a purplish tinge of the stem and flowers.
         Both are narcotic and dangerously poisonous.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Datura
    n 1: thorn apple [syn: Datura, genus Datura]